update for some jupyter_client 7.0 API changes
When I tried to install knitty this morning it did not work for me! I figured out that my issues were caused by the recent 7.0 update of the jupyter_client package, which changed the API a bit.
This PR contains the changes required to make my instance of knitty work again. I am not sure if I fully updated the package to jupyter_client 7.0, though I doubt there would be many I missed.
Thanks for this wonderful package, it is exactly what I've been looking for!
Unless I missed it, I recommend you mention somewhere that numpy and matplotlib are required for the tests!
I reviewed the rest of the 7.0 API changes, and it looks like the ones I caught were the only ones that needed changing. I recommend you lock the jupyter_client package to a 7.0+ version.